Process for conversion of alkyl aromatic hydrocarbons

ABSTRACT

A DISPROPORTIONATION AND TRANSALKYLATION OF AN ALKYLAROMATIC HYDROCARBON CAN BE CONDUCTED BY USE OF A SUPPORTED CATALYST OF A MORDENITE CARRYING A COMBINATION OF ZR AND ANOTHER METAL SELECTED FROM THE GROUP CONSISTING OF BI, NB, AG, CU, MO, SB AND Y.

United States Patent Oflice 3,819,736 PROCESS FOR CONVERSION OF ALKYLAROMATIC HYDROCARBONS Yuji Sato and Hideyuki Takahashi, both MitsubishiPetrochemical Co., Ltd., Technical Development Research Laboratory, 1Toho-cho, Yokkaichi, Japan No Drawing. Continuation-impart of abandonedapplication Ser. No. 142,405, May 11, 1971. This application Nov. 14,1972, Ser. No. 306,290

Int. Cl. 'C07c 3/62 US. Cl. 260-672 T 5 Claims ABSTRACT OF THEDISCLOSURE A disproportionation and transalkylation of an alkylaromatichydrocarbon can be conducted by use of a supported catalyst of amordenite carrying a combination of Zr and another metal selected fromthe group consisting of Bi, Nb, Ag, Cu, Mo, Sb and Y.

CROSS REFERENCE TO RELATED APPLICATION This application is aContinuation-In-Part of copending application Ser. No. 142,405, filedMay 11, 1971 and now abandoned.

BACKGROUND OF THE INVENTION Field Of The Invention This inventionrelates to a process for the disproportionation and the transalkylationof alkyl aromatic hydrocarbons.

Description Of The Prior Art Various processes for disproportionatingand transalkylating alkyl aromatic hydrocarbons have been disclosed inthe prior art, however, many of those processes have been found to be atleast partially unsatisfactory when used on a large-scale industriallyacceptable basis.

It has been disclosed that H-mordenite or H-faujasite of zeolite wasused as a catalyst for disproportionating alkyl aromatic hydrocarbon.See Journal of Catalysis; Volume 8, Page 371 (1967). However, the typesof catalysts disclosed in that reference have relatively low conversionactivity and poor selectivity etc. It has been known that catalysts madeof zeolite and catalytic metals such as Ag, Ni were used fordisproportionation of toluene, however, only about 40% conversion waspreviously obtainable. Most conventional catalysts suffer from thedisadvantages of low catalytic activity, low durability, and smallliquid space velocity.

SUMMARY OF THE INVENTION Accordingly, it is an object of this inventionto provide a novel process for disproportionation and transalkylation ofalkyl aromatic hydrocarbons at a high rate and high degree of conversionand at high selectivity,

It is another object of this invention to provide a process fordisproportionation and transalkylation of alkylaromatic compounds todecrease non-aromatic components especially, non-aromatic componentshaving boiling points 1 similar to the boiling point of benzene.

Patented June 25, 1974 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTSThe starting materials of the process of this invention are alkylaromatic hydrocarbons, which include toluene, xylene, ethyl-benzene,pseudocumene, mesitylene, ethyltoluene, hemimellitene, cumene,isodurene, durene and cymene, and mixtures of said compounds with otheralkyl aromatic hydrocarbons or other hydrocarbons, such as benzene.

The mordenite carriers used in this invention are preferably thesynthetic mordenite. The mordenite can be used as a carrier for thespecific catalytic metal, although it is preferred to use the mordeniteafter replacing the alkali metal of said mordenite with the specificcatalytic metal.

In order to increase the mechanical properties of the resultantcatalyst, it is possible to admix an acid clay, silica-alumina, silica,alumina and activated clay or other clay with the mordenite as a binder.The catalytic metals of Zr, Nb, Bi, Ag, Cu, Mo, Sb and Y can be carriedby various processes and preferably by ion-exchange.

In supporting the catalytic metal, a variety of compounds can be used,including zirconyl nitrate, zirconium chloride, zirconium sulfate,niobium pentachloride, bismuth nitrate, bismuth oxide, bismuth phosphateand bismuth hydroxide.

Other metal compounds, such as silver nitrate, cop-per nitrate, antimonytrichloride, antimony oxide and ammonium molybdate can be used incombination with the catalytic metal. Good results are obtainable whenthe catalytic metal is supported on the mordenite by an ion-exchancetechnique. It is possible, however, to apply the catalytic metal salt tothe mordenite by heat reducing a salt of said metal in the presence ofhydrogen.

Thus, when using the present catalyst the hydrocracking of aromaticcompounds forming non-aromatic compounds is highly controlled and thelife of the catalyst is remarkably increased.

It is preferable to carry 0.01-10 wt. percent, especially 0.02-5 wt.percent of Zr on the mordenite, and it is preferable to carry 0.01-20wt. percent, especially 0.05-10 wt. percent of Bi, Nb, Ag, Cu, Mo, Sb orY on the mordenite together with Zr.

The ratio of Zn used relative to the second metal component of thecatalyst is l:0.1-20 and preferably 1:1-20. Best results are attained ata ratio of 1:1-10. The ratio of Zr to the metal selected from Bi, Nb,Ag, Cu, Mo, Sb or Y to Zr is usually 1:0.1-20, preferably 1:1-20,especially 1:1-10.

Where the quantity of catalytic metal on the mordenite is too high, theactive surface area of the catalyst will be decreased and the activityof the catalyst will be decreased. Moreover, use of an excess quantityof catalytic metal is uneconomical in view of the relatively high costof the catalytic metal.

In order to prepare a high crush strength catalyst, characterized byhigh catalytic activity, it is preferable to use an acid clay, anactivated clay, a silica-alumina or an alumina as a binder for themordenite. Best results are obtainable when 3-95 weight percent of thebinder is used with the mordenite. Where the amount of binder used isless than 3%, the strength of the carrier will be insufiicient, and ifit is greater than the catalytic activity will be decreased, althoughthe crush strength will be quite high. Suitable acid clays used for thispurpose are those having a specific area of -200 mF/g. and suitableactivated clays, are those having a specific surface area of 200-350 m.g.

One suitable method for preparing the catalyst of this invention willnow be described:

An aqueous solution of an ammonium salt, such as ammonium nitrate,ammonium chloride, ammonium sulfate or ammonium acetate is passedthrough a powdered or pelleted mordenite layer to exchange the sodiumion for an ammonium ion. When pellets are used, the pellet diameter maybe from 1 mm.7 mm. The entire amount of the contained Na ion can beexchanged, however, partial Na ion-exchange is acceptable. An ammoniumtype mordenite is obtained as a result of the ion exchange process.Excess ammonium salt absorbed onto or adhered to, the ammonium typemordenite can be removed by water washing, although this is optional,and good results may be obtained even without the removal of the non-ionexchange ammonium salts. The resultant product is dried at 50300 C. Ionexchange of Zirconium is then accomplished by immersing the ammoniummordenite into an aqueous solution of zirconium ion compound, mordenitefor several hours, at between room temperature and 100 C.

The partially Zr ion-exchanged ammonium type mordenite is dipped in anaqueous solution of a salt of Bi, Nb, Ag, Cu, Mo, Sb or Y at the roomtemperature 100 C. for several hours to carry the combination of 25 Zrand said metal. The higher the temperature, the faster will be theion-exchange rate, and the shorter will be the ion-exchange period.

4 EXAMPLES 1-7 A boiling solution of 8 weight percent of ammoniumnitrate was passed through pellets of mordenite of 4 mm. diameter and 4mm. length to exchange the sodium ion of said mordenite with ammoniumion. The product was repeatedly washed with water to remove completelyammonium nitrate residue. The resultant product was dried at 150 C. andthen was ion-exchanged to convert part of the ammonium ion to zirconiumion by adding an aqueous solution of the zirconyl nitrate inpredetermined catalytic amounts of said metal ion component at 90 C. for2 hours.

The resultant product was repeatedly washed with water and was dried.The resultant product was further ionexchanged by adding an aqueoussolution of each of silver nitrate, bismuth nitrate, copper nitrate,antimony trichloride, ammonium molybdate, niobium nitrate or yttriumnitrate, in predetermined catalytic amounts at 90 C. for 2 hours. Eachproduct was washed with water and was dried at 150 C. and was furtherheated at 600 C. for 2 hours, to obtain each catalyst used in thefollowing examples:

The disproportionation of toluene was conducted using 100 ml. of saidcatalyst at 500 C. at a pressure of kg./cm. G and a liquid hourly spacevelocity (LHSV) of 2 hr.- at a molar ratio of H to toluene of 5:1.

The results are summarized in Table 1.

TABLE 1 Example 1 2 3 4 5 6 7 Catalytic metal Zr-Ag Zr-Bi Zr-Cu Zr-MoZr-Sb Zr-Nb Zr-Y Zr: 0.5 Zr: 0.5 Zr: 0.5 Zr: 0.5 Zr: 0.5 Zr: 0.5 Zr: 0.5Ammmt metal Ween) Ag: 1.0 Bi: 0.8 Cu: 0.9 M0: 0.9 Sb: 0.9 Nb: 1.0 Y: 1.4

Carrier Mordenite Mordenite Mordenite 85% mor- 85% mor- 85% mor-Mordenite denite denite denite 15% acid 15% acid 15% acid clay clay clayReaction conditions:

Pressure (kg/cm. G) 50 50 50 50 50 50 HQ/toluene (molar ratio)... 5 5 55 5 5 5 LHSV hr.' 2 2 2 2 2 2 2 Temperature C.) 500 500 500 500 500 500500 Conversion of toluene (mole percen 54. 4 54. 6 52.0 53. 6 54. 8 52.2 55. 0 Disproportionation ratio (molar ratio) 0.88 0. 92 0. 92 0. 92 0.93 0. 93 0. 88 Loss of aromatic components [mole percent] l. 2 1. 4 1.3 1. 1 1. 1 1. 3 1.2

l Disproportlonation ratio is shown in molar ratio of resultantxylenefbenzene.

Non aromatics [mole percent] The mordenite thus provided is then washedwith water, dried and carefully heated to 300-1000 C. for several hours.If the heating is too rapid the crystalline structure of the zeolite maybe damaged.

The disproportionation and transalkylation of an alkyl aromatichydrocarbon can then be conducted by using the catalyst under variousreaction conditions, such as at a temperature in the range of from about200 C. to 800 C., under atmospheric, high or low pressures and at therate of 0.1-20 hour" of liquid hourly space velocity 60 (LHSV).

It is possible to introduce hydrogen with the starting material in therange of 0-20 molar ratio of hydrogen to the alkyl aromatic hydrocarbon.Where hydrogen is introduced in the disproportionation andtransalkylation process, it is possible to maintain the activity of thecatalyst for a longer period of time.

It is also possible to introduce an inert gas, such as nitrogen intosaid reaction system of conversion of alkyl aromatic hydrocarbon.

Having generally described the invention, a further understanding can beattained by reference to certain specific Examples which are providedherein for purpose of illustration only and are not intended to belimiting in any manner unless otherwise specified.

REFERENCE EXPERIMENT l-8 A boiling solution of 8 Weight percent ofammonium nitrate was passed through pellets of mordenite of 4 mm.diameter and 4 mm. length to exchange the sodium ion of said mordenitewith ammonium ion. The product was repeatedly washed with water toremove completely ammonium nitrate residue. The resultant product wasdried at 150 C. and then was ion-exchanged to convert all or a part ofthe ammonium ion with one of the following metal ions, by adding anaqueous solution of the corresponding metal compound, in predeterminedcatalytic amounts, at C. for 2 hours.

The resultant product was repeatedly washed with water and was dried andthen was heated at 600 C. for 2 hours.

In these examples, the metal compounds used for said ion exchange weresilver nitrate, bismuth nitrate, copper nitrate, ammonium molybdate,antimony trichloride, niobium nitrate or yttrium nitrate.

The disproportionation of toluene was carried out using ml. of saidcatalyst, at 400 C.500 C. under a pressure of 50 kg/cm? G and liquidhourly space velocity [LHSV] of 2 hr. at a molar ratio of H to tolueneof 5:1.

The results of said disproportionation, using these catalysts aresummarized in Table 2.

6 H-type mordenite, were respectively used for disproportionation oftoluene. The results are shown in Table 4.

TABLE 2 Reference experlment-- 1 2 3 4 5 6 7 8 Catalytic metal Ag Bl CuMo Sb Nb Y Zr Amount of metal (wt. percent) 1.0 0. 8 0. 9 0. 9 0. 9 1.2 1. 4 1. 1

Carrier Mor- Mor- Mor- 85% mor- 85% mor- Mor- Mor- Mordenite denitedenlte denite denite denite denite denite acid 15% acid clay ay Reactionconditions:

Pressure (kg/cm. G) 50 50 50 50 50 50 50 50 Hz/toluene (molar ratio) 5 56 5 5 5 5 0 LHSV (hr.- 2 2 2 2 2 2 2 5 Temperature (3.). 500 500 500 500500 500 500 502 Conversion of toluene (mole percent) 52. 7 52.5 51. 051. 1 52. 3 52.0 52. 3 49. 0 Disproportionation ratio (molar ratio) 10.78 0. 86 0. 90 0. 86 0. 77 0. 84 0. 89 0. 87 Loss of aromaticcomponents [mole percent] 2 1. 8 2.0 1. 7 1. 6 1. 6 2.0 1. 7 1. 9

l Disproportionation ratio is molar ratio of resultant xylene/benzene.

Non aromatics [mole percent] 2 LOSS of ammatlc components Tolueneconversion [mole percent] As it is clear from the comparison of Examplesl-7 TABLE 4 and Reference Experiments 1-8 in accordance with the Rf t 91o 11 combination of Zr to the other metal, the conversion of fencePenman toluene was increased and the loss of aromatic co-m- Catalyst ifiiyr f y z ponents was decreased. In the conversion of the aromatic a 6mm em 8 compounds such as a disproportionation of toluene, the Reactionconditions:

R t k 2 G 6 ratio of the cost of the raw riatelnals to the costf; f theride i 0 2 5g i is uite e ectlvc r.- ,5 1 product 18 quite hlgh- Accormg q 39 Reaction temperature 500 500 to decrease the formation ofnon-aromatics. Conversion f toluene (percent 0 0 Similar tests wereconducted using the catalysts of the ilz g ratio (molar 0 75 0 58 0 82Example 2 and Reference Experiment 2, at 400 C. under 40 kg./cm. G ofpressure, 1.5 hr.- of LHSV and 10 mole/mole of H /TOL. The results areshown in Table 3.

TABLE 3 Example 8 9 Catalytic metal Bi Ar-Bi Zr: 0.5 Amount of metallwt. percent] 1.0 Bi: L0

Carrier Mordenite Mordenite Reaction conditions:

Pressure [k ./cm. G] 40 40 Hzltoluene %molar ratio] 10 10 LHSV [hr.- 1.5 1. 5 Temperature 0.] 400 400 Conversion of toluene [mole percent] 48.2 50. 5 Disproportionation ratio [molar ratio]. 0. 88 0. 90Non-aromatics yield [mole percent] 0. 6 0.3 Methylcyclo pentane contentin liquid product [mole p.p.m.] 137 38 Cyclohexane content in liquidproduct [mole p.p.m.] 31 11 As it is clear from the results of the Table3,, is was found to be that the quantity of non-aromatics having boilingpoints similar to the boiling point of benzene such asmethylcyclopentane and cyclohexane etc., were decreased when using thecatalyst supporting a combination of Zr and another metal.

Since it is diflicult to separate the non-aromatic components frombenzene, by distillation, a decrease in the quantity of non-aromaticsbeing obtained results in an increase in purity of the benzene. TheOperation of the benzene tower is thus made easier and the economics ofthe process is improved.

REFERENCE 9-11 In order to show the superiority of the new catalyst ofthis invention, to conventional catalysts characterized by high activityfor the particular type of disproportionation; such as silica-aluminacatalyst, H-type faujasite and 1 Resultant xylene/benzene (molar ratio).

It is clear that the catalysts of this invention shown in Table l, aresuperior to the conventional catalysts, shown in Table 4, in conversionof toluene and disproportionation ratio.

The thermodynamical equilibrium conversion of toluene to producebenzene, 0-, m-, and p-xylene by disproportionation of toluene at 500 C.is 56.8%. Accordingly, the conversion made by using the catalyst of theinvention is near the thermodynamical equilibrium conversion.

EXAMPLE 10-14 AND REFERENCE 12-15 Powder form mordenite and the binderwere mixed and then about 200 weight percent of water was added to themixture. The mixture was kneaded and shaped by the extruder and then wasdried at C. for 3 hours and was heated at 600 C. for 2 hours.

The pellets were dipped in an aqueous solution of 1 Weight percent ofzirconyl nitrate to effect ion-exchange. The product was then calcinedat 600 C. for 2 hours to obtain the catalyst.

As a reference, the same process was repeated except without a binder inthe catalyst (Reference 14) or with 15 weight percent of Kaolin(Reference 15). Each catalyst contained 1.1 weight percent of zirconiumand had a 3 mm. diameter and a length of 7 mm. respectively. The resultsof crushing strength tests of the catalysts, and the disproportionationactivities of toluene using said catalysts are shown in Table 5.

The measurement of crushing strength was made by pressing the catalystwith the hardness tester using a piston of 0.5 cm. of circular section.

The disproportionation of toluene was conducted at 500 C., at a pressureof 50 kg./cm. G, and a space velocity LHSV of 2 hrr The molar ratio of Hto toluene was 5:1.

TABLE Example 11 12 13' 14 14' 15 Zeoli Mnrdenite Mordenite MordeniteMordenite Mordenite Mordenite dig?- e to Acid Activated Silica- Silica-Silica- Binder clay l clay I alumina alumina alumina 1 None Kaolin Rateof binder (wt. percent) 15 15 15 3 50 0 15 Crushing strength of catalyst(kg. /0.5 cm. catalyst side) 7. 6 7. 5 7. 5 1. 5 7. 5 0. 8 6. 5Conversion of toluene (mole percent) 52.6 52. 3 49.8 49. 7 49. 6 49. 743. 5 Resultant xylene/benzene (molar ratio) 0.87 0- 87 0. 88 89 0.870.89 0. 89

l About 130 mJ/g. of specific surface area. 1 About 280 mfi/g. ofspecific surface area.

It is clear from the Table 5 that the catalyst using the binder of acidclay, activated clay or silica-alumina, re- 1 spectively, have excellentstrength and high catalytic activity, but the catalyst without thebinder is characterized by low strength. The catalyst using Kaolin as abinder is characterized by low catalytic activity.

EXAMPLE 15 The disproportionation of m-xylene was conducted using 30 ml.of the catalyst of Example 2, at a temperature of 450 C. under apressure of 25 kg./cm. G and a liquid hourly space velocity (LHSV) of 2hr.- The molar ratio of H /m-xylene was 5:1.

The results are shown in Table 6.

TABLE 6 Example 15. Added metal Zr-Bi. Amount of added metal (wt.percent) "{Bi, 1.0. Zr, 0.5. 1.0.

Carrier" niordenite.

15% acid clay.

Reaction condition:

Pressure (kg/cm. G).. H /m-xylene (molar rati LHSV (hrr Temperature C.)

Reaction products (mole percent): NOl'l-Bl'nm aria:

1,2,3-trimethylbenzene The disproportionation of m-xylene was quitegood, and the ratio of isomers of xylene fraction of the reactionproduct are the same as the thermodynamical equilibrium. Accordingly, itis clear that the catalyst is quite effective for isomerization of alkylaromatic hydrocarbon.

EXAMPLES 16-18 The transalkylation reactions of toluene and pseudocumenewere made using 100 m. of the catalyst used in Example 1. The reactionconditions were 50 kg./cm. G of reaction pressure, 5 molar ratio of H/Starting materials, 1 hr.- of LHSV and 500 C. of reaction tempera- 3Silica:alumina=87:13.

" Reference.

It is clear from Table 7 that excellent transalkylation of alkylaromatic hydrocarbon is made by using the catalyst of this invention.

We also have found that the other catalysts were also quite active forthe transalkylations of alkyl aromatic hydrocarbons as well as thatAr-Ag mordenite catalyst.

Having now fully described the invention, it will be apparent to one ofordinary skill in the art, that many changes and modifications can bemade thereto without departing from the spirit or scope of theinvention.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:

1. In a process for disproportionation and transalkylation ofalkyl-aromatic hydrocarbon the improvement comprising effecting saiddisproportionation and transalkylation in the presence of a supportedcatalyst of a mordenite carrying a combination of 0.01 to 10 wt. percentZr and 0.5 to 10 wt. percent of another metal selected from the groupconsisting of Bi, Nb, Ag, Cu, Mo, Sb. and Y.

2. The process for disproportionation and transalkylation of alkylaromatic hydrocarbon according to Claim 1. wherein the catalyst isprepared by exchanging the alkali metal ion of the mordenite with saidspecial catalytic metal ions.

3. The process of disproportionation and transalkylation of alkylaromatic hydrocarbon according to Claim 1, wherein the alkyl aromatichydrocarbon is selected from the group consisting of toluene, xylene,ethylbenzene, pseudocumene, mesitylene, ethyltoluene, hemimellitene,cumene, isodurene, durene and cymene.

4. The process for disproportionation and transalkylation of alkylaromatic hydrocarbon according to Claim 1, wherein the alkyl aromatichydrocarbon is converted in the presence of hydrogen gas.

5. The process for disproportionation and transalkylation of alkylaromatic hydrocarbon according to Claim 1, wherein the mordcnite isshaped'with a binder selected from the group consisting of acid clay,activated clay and silica-alumina.

References Cited UNITED STATES PATENTS 3,597,491 8/ 1971 Kovach et al.260-672 T 3,598,878 10/1971 Kovach et a1 260-672 T 3,699,181 10/ 1972Kmccak et a1 260-672 T CURTIS R. DAVIS, Primary Examiner

